Gas insulated high voltage circuit breakers are commonly located in electrical distribution sub-stations and selectively open and close electrical connections therein. One such prior art circuit breaker is the three-pole circuit breaker 10 shown in FIGS. 1-3. The high voltage circuit breaker 10 includes three poles 12. Each pole 12 includes a tank 14, a pair of outwardly extending bushings 16, and current transformers 18 proximate to the intersection of each bushing 16 and tank 14.
The poles 12 are mounted to a pair of support brackets 20 positioned at opposing ends of the poles 12. Support brackets 20 are coupled to a frame 22 having a plurality of interconnected metal linkages. Frame 22 is also coupled to an operating device 24 that includes a protective cabinet 26 that houses the operating electronics as well as the breaker actuating mechanism. As is well known in the art, the operating electronics may (either by sensing a fault or when receiving a control command from an exterior source) command the actuating mechanism to move an actuating rod 28, which causes the breakers to open or close.
Circuit breakers 10 are relatively large assemblies, and thus shipping costs are a non-trivial portion of the overall cost of the breaker. In order to reduce these costs, breakers 10 are commonly shipped disassembled, so that smaller shipping containers may be used. This is facilitated by, for example, removing the frame 22 and operating device 24 from the subassembly including the poles 12 and support brackets 20. Frame 22 may be further disassembled into the constituent metal linkages.
Regarding the pole/bracket subassembly, the overall size was reduced for shipping by placing the poles 12 in a shipping configuration (See FIG. 3) which occupies a smaller area than the installed configuration (See FIG. 2). In the installed configuration, the bushings 16b of the center pole 12b extend substantially perpendicular to the ground (when viewed from the front). For purposes of electrical isolation of the phases, the bushings 16a,c of the two outer poles 12a,c are angled away from the bushings 16b of the center pole 12b. Each pole is fixed to support bracket 20 positioned at each end of the poles 12. The poles 12 are secured to support bracket 20 by three bolts at each end.
With reference to FIG. 3, when in the shipping configuration, the outside poles 12a,c are pivoted inwardly toward center pole 12b, such that all three bushings 16 are parallel with each other and perpendicular to the ground (when viewed from the front). This was accomplished by removing the outer two bolts 30 on each end and then pivoting the pole 12 about the remaining, inner bolt 32. Once aligned in the shipping configuration, a shipping bracket 34 is bolted to both the support bracket 20 and poles 12a,c to retain the outer poles 12a,c in the shipping configuration. When the installation site is reached, the shipping brackets 34 were removed, allowing the outer poles to pivot outwardly and be secured in the installed position.
The above described method and configuration does enable the use of smaller shipping containers and the corresponding reduction in shipping costs. However, drawbacks remain. For example the outer bushings 16a,c extend higher than center bushing 16b, thereby adding to the shipping container size. Further, the act of pivoting the pole can be difficult and cumbersome.
Thus, there is a need in the art for a high voltage breaker assembly that is optimized to reduce the costs of shipping and the labor involved in on-site assembly.